Our proposed research is concerned with quantitative mapping of the biological distribution of administered radioactive tracers in man an experimental animals using imaging techniques. Specifically the research projects deal with: (1) continued efforts to ellucidate the relationship between chemical structure and the biological distribution of technetium compounds; (2) development of new methods for radiolabeling monoclonal antibodies with technetium-99m; (3) design of new radiolabeled lipophillic cations and ellucidation of their mechanism of accumulation in the heart; (4) further synthesis of ligands for study of the cholinergic system; and (5) continued investigations of the relationship between chemical structure and the biological distribution of compounds bound by opiate receptors. The program is multidisciplinary, involving physicians, physicists, chemists, engineers and computer experts; and multidepartmental, involving departments of both the Schools of Medicine and Hygiene and Public Health of the Johns Hopkins Medical Institutions, and the Graduate Chemistry Division of the Johns Hopkins University. The program provides a focus for investigators in a continuing program oriented toward obtaining new knowledge about the dynamic state of body constituents by the application of a variety of new radioactive tracer techniques that we will design, develop, and evaluate.